Module apt 

apt-family package management actions (Ubuntu / Debian).

All apt commands run with DEBIAN_FRONTEND=noninteractive and NEEDRESTART_MODE=a so they never block waiting for a TUI prompt.

Lock contention

Concurrent apt runs are prevented by the dispatcher’s exclusion gate, not by a pre-flight probe: every action whose argv names an apt/dpkg tool maps to ExclusiveResource::Dpkg, and a second one submitted while the first holds that lock gets a ConflictResponse.

An earlier version of this doc claimed the executor ran fuser /var/lib/dpkg/lock before each mutating command. It never did — there is no such probe anywhere in the daemon. The gate above covers contention between SysKnife actions, which is what SysKnife can actually control; it does not detect a dpkg lock held by something outside SysKnife (an operator’s own apt session, or unattended-upgrades). In that case apt itself reports the lock and the action fails with apt’s own message.

Environment variables

DEBIAN_FRONTEND=noninteractive suppresses all debconf prompts. NEEDRESTART_MODE=a tells the needrestart post-install hook to automatically restart services instead of prompting the operator. Both are required for daemon-driven apt invocations; omitting them causes apt to hang waiting for terminal input that never arrives.

Functions

apt_autoremove

Remove automatically-installed packages no longer needed (apt-get autoremove -y).

apt_history_list

Show recent apt transaction history from /var/log/apt/history.log.

apt_hold

Pin a package at its current version (apt-mark hold <package>).

apt_install

Install a single package (apt-get install -y <package>).

apt_list_installed

List all installed packages (dpkg -l).

apt_list_upgradable

List packages that have upgrades available (apt list --upgradable).

apt_purge

Remove a package AND its configuration files (apt-get purge -y <package>).

apt_remove

Remove a package but keep its configuration files (apt-get remove -y <package>).

apt_search

Search apt repositories for packages matching a term (apt-cache search <term>).

apt_show

Show detailed information about a package (apt-cache show <package>).

apt_unhold

Remove the hold on a package, allowing upgrades again (apt-mark unhold <package>).

apt_update

Refresh the apt package index (apt-get update).

apt_upgrade

Upgrade all installed packages (apt-get dist-upgrade -y).

configure_unattended_upgrades

Enable or disable Ubuntu automatic (unattended) security updates.

specs

Return one representative ActionSpec per action name so the consistency test can verify policy + preview + executor coverage.